Spray gun



Feb. 2s, 1929.

1. BIRKENMMER SPRAY GUN 7//////////////V/////.//f.r l d 4 4i 4 f l Patented Feb. 26, 1.929.

UNITED STATES' PATENT oFFlcr..

THEODORE BIRKENMAIER, -OF BT. LOUIS, MISSOURI, ASSIGNOB, BY ml 'ASSIGN- MENTS, '.lO W. N. MATTHEWS CORPORATION, OF ST. LOUIS, IISSOUBI, A CORPORA- TION OF MISSOURI.

` SPBAY GUN.

' Application led December 29, 1922, Serial` No. 609,673. Renewed Kay 95, 1987.

This invention relates to a new and useful Iimprovement in spray guns of the ty illustrated in U. S. Letters Patent to J o ns, No. 1,361,527, dated December 7th, 1920, to Hemrich, No. 1,382,641, dated J une 28,1921, and to myself, No. 1,436,145, dated November 21, 1922.

My present invention relates-particularly to the spray nozzle and nipple of the gun, the object being to produce columns of paint, or other material, possessing dlfferent shapes and characteristics, and which columns are to be projected under air pressure agalnst the surface or wall to be coated.

One feature-of my` invention .consists 1n a relative adjustment between the nozzle and nipple, whereby a column of air of uniform pressure introduced to the nozzle, by havlng its balance or equilibrium disturbed, will produce columns of paint having different characteristics. l

Another feature of my invention is to accomplish the above by a relative longitudinal adjustment between the nozzle and the nipple.

Another feature of my invention resldes in an adjustable abutment on the trlggeroperated saddle in joint control of the air and paint valves, whereby the operation of the latter may be advanced or retarded with respect to the former.

Another feature of my invention consists in a fixed trigger stop at the point of application of the pressure on the trigger whereby it is practically impossible to spring or accidentally bend the triggerY by excessive pressure in operation. t

In the drawings:

Figure 1. is a horizontal sectional view through my improved spray Figure 2 is a front elevatlonal View of a Washer used` in the gun.

Figure 3 is a front elevational View of a gun.

Figure 4 is a front elevational view of the nipple.

Figure 5 is an enlarged horizontalsectional View through the nozzle and nipple, and

Figure 6 is a sectional view through the nozzle showing the related parts in a changed position.

In the drawings, l indicates a castino' in the form of a pistol or body having a liandle portion 2 provided with an air conduit extending through a nipple 3 to which is connected a flexible tubing leading from a source of compressed air or s supply (not shown).

4 is a nipple by w ich paint, owder, or otherv material to be sprayed, is lntroduced into the spray un. v6 indicates a trigger member pivoted y a bolt 7 to a lug extending upwardly from casting 1. Th1s trig er is preferably made of stamped metal, ghe two leg portions being integrally connected together at the top while the two lower extremities are connected by a rivet 8.

9 indicates a lug on castin 1 against which the trigger contacts when 1n its fully open position. .The presence of this lug 9 prevents the trigger being bent or s rung from excessive pressure on t e part of the operator. 10 indicates a floating saddle member with which the uppereend of the trigger co-oper ates. This saddle member is guided in its vertical movement by means of legs 10, asA

disclosed in my patent aforesaid.

In my present construction, the valve 13 which controls the air conduit to the nozzle, is operated by the saddle 10 through the medium of the valve stem 15, whereas the valve 18 which controls the admission of paint to the nipple is controlled by means of a set screw 19 (zo-operating with its stem 20, said set screw being mounted in the saddle 10. By this arrangement, the set screw 19 can be so adjusted that valve 18 will not be operated at all even though the trigger is fully retracted; or, said set screw may be adjusted so that the valve 18 will be more or less open when the trigger is retracted, or said valve 18 can be operated simultaneously with thel operation of the air valve 13. The advance or retardation of the movement of valve 18 relative to valve'13 depending upon the` las'4 The nozzle 21 has a slight clearance relative vto the barrel and in orderto prevent paint v from Aentering between the nozzle and the barrel, li provide a Washer 24 at the end of the barrel which washer is forced outwardly by means of a yielding or spreading metal washer 25.

Washer 24 is preferably made of felt or leather and the edges of Washer 25 bearing thereagainst tends to force Isaid washer tightly against the interior bore of nozzle 21. Washer 25 is held in place by means of an `enlarged body portion of the nipple 26 which cuts, preferably produced by rotary cutters so that said kerfs or cuts, are deepest at their forward endv and taper thence rearwardl 30 represents saw kerfs or cuts similarlyy ossessing similar character-- produced and istics by being eepest at their forward ends and tapering rearwardly until running out at the surface of cylindrical portion 27.

.These cuts 30 are longer than thecuts 29, but

cuts 30 terminate short of the rear end of the cylindrical portion 27 The cuts 29 and 30 function as metering slots. j The forward wall of nozzle 21 is provided with an axial bore designed to snugly receive the cylindrical portion 27 of the nipple. This central bore of the nozzle is indicated at 31 and is slightly longer than the cylindrical portion 27 which it receives.

32 indicates a concentric recess in the outer face of the front wally of the nozzle encircling the bore 31, the outer inclined wall of this craterlike recess being provided with apertures 33 arranged at diagonally opposite sides, as shown in Figure 3, and directed to 011e side of the axis of the bore 31, as shown by the arrowsin Figure 3.

. Assuming that the spray gun is connected to a supply of paint and air pressure, and the set screw is adjusted so that shortly following the opening of the air valve a supply of paint will be admitted to the nipple: If the part-s are in the position shown in Figure 6, it will` be obvious that when the air pressure is admitted in the nozzle and around the nipple, its easiest passage W1ll be through the bore 1 31, and while, of course, the ducts 33 are open,

they will not emit air under such pressure as will influence the column of air passing through the central orifice 31. Hence, with the parts in the position shown in Figure 6,

the paint, or other other material, is siphoned through the nipple and issues through the orice 3,1 practically as a solid cylindrical column enveloped by a carrying cylinder of air under pressure and possessing the requisite velocity. By adjusting the nozzle 21 rearwardly on the barrel so as to'cause the cylindrical portion 27 to enter bore 31, the passages for the air will now be so restricted that the air will be caused to pass through' the deepest portions of the circular series of lrerfs 29 and 30. Hence, the velocity of the air will be increased by these restricted openings, but the circular form of the enveloping column of air around the central column or core of paint will be preserved so that practically a solid circular pattern of paint will be made on the wall or surface to be covered.

By adjusting nozzle 21 rearwardly on the v barrel, the areas of the cuts or kerfs 29-30 are gradually decreased, and as the air meets with greater resistance at this point, its pressure and velocity builds up in the ducts 33. Finally, the inner'edge of the-end wall of nozzle 21 closes the short opeinings 29 so that only the small "shallowopenings of the cut 3() are exposed. This position of the parts builds up pressure and velocity of the air passing through the openings 30 aswell as through the ducts 33. A further adjustment of the nozzle 2l will eventually close the .openings 30, in which event the air will pass through the ducts 33 and as there is no Siphoning action in the orifice 31, the spray gun to all intents and purposes is inoperative in this condition.

It will be observed from the above description that the nozzle 21 is free to be rotatably adjusted on the barrel of the casting 1 in any longitudinally adjusted position of said nozzle; hence, the ducts 33 may be in vertical or horizontal `alignment or arranged in any angular position, depending upon the desired longitudinal I' axis 'of the fan-like spray produced by the gun.

The outer position of the nozzle, as shown in Figure 6, will cause the. gun to deliver a practically solid circular column or stream of paint, and as the nozzle is adjusted rearwardly on the barrel, the enveloping film of air is cut down in volume but built up in pressure and velocity, so that as the nozzle is adjusted rearwardly, the column of paint is more thoroughly broken up until eventually' it becomes a stream of finely atomized partj cles. As the nozzle is adj usted inwardly on the barrel, the pressure and velocity is gradually built up in the ducts 33 until the air issuing from these ports becomes effective on the column of paint.

It will be observed from Figure 3, that the blasts emitted from ducts 33 are. directed to the side edges of the column ofpaint, and hence a flattened or elliptical shaped target is produced by lateral distortion rather than pressure directed against `the center of the column.

What I claimis:

l. The combination of a spray gun',- a trigger, a valve stem, a ioating independent y movable member interposed between the i valve stem and trigger, and an adjustable part on said member for co-operating with said valve stem.

2. The combination of a spray gun, a trigger, valve stems for operating valves in c'ontrol of air pressure and paint, or the like, respectively, a oatin independently movable member interposed etween said trigger and .the ends of said valve, and means on said member and co-operating with one of said valve stems whereby the operation of its controlled valve may be advanced or retarded with respect to the operation of the other valve. i

3. In a spray gun, a. nozzle adjustably -mounted on the barrel portion of said gun,

a soft washer mounted on the forward por tion of said gun and (so-operating with said nozzle, a yielding metal Washer bearing against said soft Washer, and a nipple screwed into the barrel portion and engaging said yielding metal washer for forcing the same into spreading contact against said soft Washer.

4. In a spray gun the combination of a body having a barrel, a nozzle adjustably fitted over the barrel, a nipple in the barrel cooperating with said nozzle, sealing means at the end of the barrel, and means pressed against said sealing means by said nipple, whereby said sealing means is pressed against the barrel and the nozzle.

5. In a spray gun, a nozzle movable longitudinally on the gun and having an orifice, and a nipple having a cylindrical portion operative in said orifice, metering slots in the nipple ada ted to be covered and uncovered by the nozz e as it moves relatively to the nipple, supplementary ducts in the nozzle, means for supplying air to the nozzle, whereby air is ejected through at least some of said slots and the supplementary duct-s in proportion depending upon the metering action of said ducts in a predetermined position of said nozzle.

In testimony whereof I hereunto aix my signature this 24th day of November, 1922.

THEODORE BIRKENMAIER. 

